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					                                                                        Humans in Space
                                                                        Colonizing the galaxy
http://library.thinkquest.org/C003763/index.php?page=future05



To answer some of your questions you might have             100,000 light years in diameter and that we are
on this topic, we've decided to create a little             30,000 light years from the centre, the further star
question and answer session. Read on...                     away from us is about 70,000 light years away. At
                                                            one-fourth the speed of light, it'll take 280,000
                                                            years to get there."
"What is this, science fiction? Colonizing the solar
system I can believe, but colonizing the galaxy?
Aren't there billions of stars out there?"                  "Okay, okay. But that's not what's important. How
                                                            on Earth can this be done?"
"Roughly 200 billion, according to current estimates.
And yes, it would be possible to colonize the galaxy        "Think about it. It's likely, as we mentioned in
in a relatively short period of time."                      Interstellar Travel, that any interstellar spacecraft
                                                            will be powered by nuclear fusion. While nuclear
                                                            fusion is not yet viable, it may well be within the



  Two hundred billion stars. One hundred thousand light
  year diameter.




                Just how on Earth do we think we can colonize the
                                               Milky Way galaxy?

"How short is relatively short?”                            next few decades. Fusion requires helium-3 as fuel,
                                                            and we have very little helium-3 on Earth."
"Well, we're talking on geological and cosmological
timescales here. Consider the fact that a million           "Ah, so we won't have enough fuel, right?"
years to a star is less than one five thousandth of
its entire life."
                                                            "Wrong. There are large amounts of helium-3 on the
                                                            Moon, and vast quantities of helium-3 in Uranus."
"You're avoiding the issue here. How long?"
                                                            "Yeah, you say 'vast' but there can't possibly be
"Possibly just less than 300,000 years, so long as          enough for even a hundred interstellar spacecraft."
you travel at about 25% the speed of light."
                                                            "Really? It's been worked out that just one percent
"How did you work that out?”                                of the helium-3 on Uranus would be enough to send
                                                            one ship to every single star in the galaxy, and each
                                                            of those ships could carry a billion people.
"Considering that the Milky Way galaxy is roughly
                                                            Generation ships? More like world-ships."


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                                                                        Humans in Space
                                                                        Colonizing the galaxy
http://library.thinkquest.org/C003763/index.php?page=future05



"I don't believe it!"                                       negative mass matter, then it's a completely
                                                            different ball game."
"It's true. Although I have to admit I haven't been
completely honest with you on all the facts."                              et
                                                            "Absolutely. Y is this really going to happen? Do
                                                            you really think that we'll send self-replicating
                                                            interstellar probes to other stars?"
"Ah, just as I thought. The whole thing is a sham."

                                                            "It's a possibility. It's always very difficult to predict
"No, it isn't. While there might be enough helium-3
                                                            the future. In fifty or a hundred years time, the
on Uranus to fuel two hundred billion interstellar
                                                            world will be a completely different place. We'll
craft, we'd never be able to build all of those ships
                                                            have artificial intelligences that are magnitudes of
with the resources in the Solar System. And as you
                                                            times more intelligent than us. We'll be able to
know there aren't enough people alive to send a
                                                            effectively live for at least 200 years or more.
decent number to every star in the galaxy. So what
                                                            Computers will be unimaginably powerful - we
would probably happen is that a first wave of
                                                            might even be able to download ourselves into
automatic, unmanned interstellar probes would be
                                                            computers. Will we still want to colonize the galaxy
sent to a small number of stars. Those probes
                                                            in that sort of world? I don't know."
would self-replicate and mine their systems of
resources to produce habitats for humans. Finally,
they would then produce more probes, mine more              "Hold it. Exactly why did we want to colonize the
helium-3 and travel to another system. Once that's          galaxy in the first place?"
done, humans can come along and settle down in
the ready-made habitats. If you plot a conservative
                                                            "That's an interesting question. We wouldn't
exponential chart of this process, it would only take
                                                            necessarily be colonizing the galaxy - I find it hard
ten to a hundred million years to colonize the entire
                                                            to believe we'll even colonize one percent of all the
galaxy."
                                                            stars. We'll be exploring, looking for other intelligent
                                                            life. And surely it's worth anything to be able to go
"A bit longer than 280,000 years, eh?"                      and encounter aliens? Imagine what we could learn
                                                            and what we could see on those journeys..."
"Yes, just slightly.”
                                                            "Stop going all poetic on me."
"Wait, hold on a second. Self-replicating probes?
Interstellar travel? Isn't this all a bit science           "Sorry. Also, if the galaxy turns out to be tragically
fictiony?"                                                  lifeless, by colonizing the galaxy we would be
                                                            spreading it with life and richness. Wouldn't a living
                                                            galaxy be a more interesting and better place than a
"Going to the Moon was science fictiony in 1900,
                                                            sterile, dead galaxy.”
wasn't it?"

                                                            So there you go, colonizing the galaxy in under a
"Hmm. Fair enough."
                                                            hundred million years.

"Of course, all of this talk is based on the
                                                              Image on previous page: Infrared photograph of
assumption that faster than light travel is not
                                                              the Milky Way galaxy taken by the COBE space
possible. If we did somehow manage to travel faster
                                                              telescope. Courtesy NASA/COBE.
than light, maybe using stabilized wormholes with


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